docs: update prerequisites matrix OCR defaults to v2 (Randy review)

Address PR #2166 review: main branch Helm chart defaults to Nemotron OCR v2
(nemotron-ocr-v2:1.4.0). Remaining OCR documentation and chart code in #2259.

Author: kheiss-uwzoo

docs/docs/extraction/prerequisites-support-matrix.md

@@ -71,20 +71,20 @@ The production Helm chart enables these NIM microservices **by default** (for ex
 |-----------|-----|------|
 | `page_elements` | [nemotron-page-elements-v3](https://huggingface.co/nvidia/nemotron-page-elements-v3) | Page layout and element detection |
 | `table_structure` | [nemotron-table-structure-v1](https://huggingface.co/nvidia/nemotron-table-structure-v1) | Table structure extraction |
-| `ocr` | [nemotron-ocr-v1](https://huggingface.co/nvidia/nemotron-ocr-v1) | Image OCR |
+| `ocr` | [nemotron-ocr-v2](https://huggingface.co/nvidia/nemotron-ocr-v2) | Image OCR |
 | `vlm_embed` | [llama-nemotron-embed-vl-1b-v2](https://huggingface.co/nvidia/llama-nemotron-embed-vl-1b-v2) | Multimodal (VL) embedding |
 
 ### OCR artifacts (Helm vs local Hugging Face) { #nemotron-ocr-v2-language-mode }
 
 !!! note
 
-    **Helm / NIM:** The production chart deploys **Nemotron OCR v1** under `nimOperator.ocr` (`nvcr.io/nim/nvidia/nemotron-ocr-v1:1.3.0`). For image defaults and upgrade notes, refer to [OCR NIM configuration](https://github.com/NVIDIA/NeMo-Retriever/blob/26.05/nemo_retriever/helm/README.md#ocr-nim-configuration) in the Helm chart README.
+    **Helm / NIM:** The production chart deploys **Nemotron OCR v2** under `nimOperator.ocr` (`nvcr.io/nim/nvidia/nemotron-ocr-v2:1.4.0`). For image defaults and upgrade notes, refer to [OCR NIM configuration](https://github.com/NVIDIA/NeMo-Retriever/blob/main/nemo_retriever/helm/README.md#ocr-nim-configuration) in the Helm chart README.
 
     **Local Hugging Face inference:** When you deploy locally with HuggingFace model weights (for example `pip install "nemo-retriever[local]"` and GPU inference without remote OCR NIM URLs), the default OCR engine is **Nemotron OCR v2**, which runs in **multilingual** mode by default. For CLI flags and API parameters, refer to [Nemotron OCR v2 — language mode](https://github.com/NVIDIA/NeMo-Retriever/blob/main/nemo_retriever/docs/cli/README.md#nemotron-ocr-v2-language-mode). Remote OCR NIM endpoints use their own model and language behavior; local OCR language selectors are not sent on remote requests.
 
 Default OCR NIM container for release Helm deployments:
 
-- **Image:** `nvcr.io/nim/nvidia/nemotron-ocr-v1:1.3.0`
+- **Image:** `nvcr.io/nim/nvidia/nemotron-ocr-v2:1.4.0`
 
 Default VL embedder container and model for release deployments: